The present invention is directed toward a concrete anchor and, more particularly, toward a concrete anchor that is adapted to be connected the lanyard of a harness of a construction worker to help prevent injury to the worker in the event of a fall.
During the construction or repair of buildings, bridges, road overpasses and other structures, workmen of various specialties frequently have to work at high elevations. To prevent injuries from falls, these workmen are provided with a harness and lanyard. Frequently, the lanyard is connected to a fall safety device such as described in U.S. Pat. No. 4,511,123 which issued to the present Applicant and which controls the decent and stops a worker from falling. In any event, the lanyard or the fall safety device must be secured to a fixed part of the structure. This can be directly to part of the iron work or to a horizontal life line such as shown in U.S. Pat. No. 6,640,727 which also issued to the present Applicant.
There are, however, times when iron work or the like is not available and the lanyard or lifeline must be secured directly to a concrete slab. The concrete may be a floor or wall or even a concrete ceiling. To accomplish this, concrete anchors have been proposed and marketed in the past. To Applicant's knowledge, however, none has been satisfactory.
U.S. Pat. Nos. 6,729,821; 7,011,281 and 7,357,363 to Guthrie et al, for example, describe an expansion bolt that can be used in the construction industry and which is intended to be inserted into a bore formed in a concrete slab. The anchor shown therein includes a pair of semi-cylindrical outer chucks that are forced apart by an inner cone when a pulling force is applied to the cone. It has been found, however, that the patented anchor is not always reliable and can slip out of the bore if sufficient force is applied.
A similar arrangement is taught in U.S. Pat. No. 7,258,316 to Reeves. This patent also shows a pair of semi-cylindrical outer chucks forced apart by an inner conical or tapered member. As with the Guthrie et al. device, the Reeves' anchor can slip if sufficient pulling force is applied.
Steel balls that are forced outwardly by an internal cone or cam when the cam is axially moved have also been known. However, these function primarily as quick release locking pins rather than anchors. See, for example, U.S. Pat. No. 6,386,789 to Chausse et al. and U.S. Pat. No. 7,736,109 to Schiemer, II. To Applicant's knowledge, devices such as these have never been designed to function as concrete anchors.
Because the prior art has not proven to be satisfactory, a need exists for a concrete anchor that can be quickly installed but which will safely and effectively hold in place so as to protect a worker from injury in the event of a fall.